Fenianeen — diminutive of "Fenian": loosely, as used here, any Irish nationalist of "advanced" or "militaristic" opinion. ((fenian: "a rebel, patriot; a Catholic, a nationalist" – Slanguage.)) (("the candidate should be a safe man, one who would support 'the party,'—not a cantankerous, red-hot semi-Fenian, running about to meetings" – Trollope, Phineas Finn, 1869.)) Fenians

rateable value — (("value ascribed to a property for the purpose of assessing the rates to be levied on it" – OED.)) In plainer words, the houses become richer-looking as he advances.

boys ... bugles ... bayonets — their army career together, i.e. from being army boys through buglers to "bayonets" (("a synonym of 'rank and file,' that is, privates and corporals of infantry" – Brewer 1898.))

rang like bells ... — ? chimed together, in the sense of being agreeable. all we wanted was hanging — punning "hanging bells" and "hanging criminals". (("agree like bells, they want nothing but hanging": colloquial verging on proverbial – Partridge HS.)) Mr Mack's and Mr Doyle's thoughts upon each other seem to circle the notion that one or the other or both should be hanged. cf "by any stretch" Prologue <; "never your neck", Ch1.1. <

light of bright and other days — reference to the song "Oft in the Stilly Night", by Thomas Moore, 1815, which Mr Doyle will sing in Chapter 3.2. ("Sad memory brings the light | Of other days around me".) ♫♫

hatches, matches, dispatches — newspaper column of births, marriages, and deaths. ((journalistic – Partridge HS.)) The front page of newspapers then was usually reserved for announcements and advertisements.

Roll of Honour — here, a newspaper column reporting war casualties.

scapular — a devotional adornment worn by Catholics, often as a protection against temptation or evil. ^

borrowing trouble — going out of one's way to meet trouble. ((OED.))

Jacobs! — a minced oath for "Jesus!" ("based on the name of a well-known Biscuit manufacturer in Dublin" – DHE.))

two dee — two pennies. (Mr Mack had paid for the newspaper with a threepence coin.) one and thruppenny — costing one shilling and threepence.

Ballygihen House — from the descriptions a mixture of someplace real and someplace imagined. ^

on me — the meaning is "to my disadvantage" rather than "on my head". IE

G.A Dunn & Co., bowler hat

Dunn's three-and-ninepenny bowler — from Dunn & Co, the Strand, London hatters. (("This make being the best of the lower-priced hats" – Partridge HS.))

the sea oh the sea, long may it be — ? an echo (or, given the period, a presentiment) of the song "The Sea Around Us" by Dominic Behan, written in the 1960s. ♫♫

view and vantage them both — both pleasant to look at and commanding a pleasant view.

RMS Munster, one of the four mailboats to England

mailboats — the passenger boats that plied between Kingstown and the British ports, carrying the mail. ^

area and steps

area steps — steps leading to the "area". ((area: "sunken court, shut off from the pavement by railings, and approached by a flight of steps, which gives access to the basement of dwelling-houses" – OED.)) The area usually constituted the servants' entry.

slavey — maid-of-all-work, general maid. (("esp. one who is hard-worked" – OED.)) (("... the young woman who did the work of the house, and who was known by the name of Betty to her mistress, and of 'Slavey' to Mr. Morgan" – Thackeray, Pendennis, 1850.)) (("... she told me she was a slavey in a house in Baggot Street" – Joyce, Dubliners, 1914.))

showing leg — revealing a part of her leg as she worked.

Athlone — a town in County Westmeath located close to the geographical centre of Ireland.

big house — a mansion. ((OED.)) (("the 'Big House,' as an Irish country gentleman's residence is termed" – Carleton, "Traits and Stories of the Irish Peasantry, Vol 3, 1833.)) (("the gentry have gone and the big houses are in ruins, or empty or sold to nuns and monks, who are the only people who can afford to live in fine houses" – George Moore, Hail and Farewell, Vol 3, 1914.))

gigglepot — ? somebody who giggles and twitters. The word doesn't appear in any dictionaries.

Recruitment poster, WW1

rights of Catholic Belgium — Belgium, a largely Catholic country, had been invaded by Germany at the start of the War. In consequence in Ireland the "major propaganda arguments for joining the British army focused (for southern Catholics) on defending the Catholic nation of Belgium ..." – Donnelly, Encyclopedia of Irish History and Culture, 2004.

nipper-squeak — the squeak, or high-pitched call, of a young boy. ((nipper: "a boy, esp. if under say 12" – Partridge.))

tram had passed — it appears trams at this time made small deliveries. (("Among other facilities offered by the D.U.T.C. [Dublin United Tramway Company] was the Parcels Express, which operated from 1883 to 1940" – Dublin Tramways.)) (("Can you send them by tram? Now?" – Joyce, Ulysses, 1922.))

Adelaide Road — probably named after Queen Adelaide, consort of King William IV (reigned 1830-37).

Sawney — Scottish lowlands variant of "Sandy" short for the masculine name "Alexander". Here, presumably, a shortened version of "Alexandria", though this usage is nowhere reported. The OED gives three further meanings: 1. derisive nickname for a Scotchman; 2. a simpleton, fool; 3. slang bacon.

Straits of Ballambangjan — (("straits as imaginary as they are narrow" nautical colloquial – Partridge HS.)) (("A sailor's joke for a place where he may lay any wonderful adventure. These straits, he will tell us, are so narrow that a ship cannot pass through without jamming the tails of the monkeys which haunt the trees on each side of the strait; or any other rigmarole which his fancy may conjure up at the moment" – Brewer 1898.))

Mr. A. Mack, Esqr. — Mr Mack here both assumes a dignity (Esqr, short for Esquire, "a man belonging to the higher order of English gentry" – OED) and forfeits it ("Esqr" supersedes "Mr" and may not be used in connection with it). ^

blacking — the application of black-lead (polish for cleaning and shining ironwork.) Zebra — a brand of black-lead.

hero who avenged Khartoum — Field Marshal Lord Kitchener, known as "Kitchener of Khartoum". ^

Findlater's, George's St, Kingstown"Under the Findlater's Clock" was for years the rendezvous for Dun Laoghaire's patient lovers.

Findlater's — a large "genteel" grocery store in nearby Kingstown.

his treat — his (birthday) present.

I'll be sugared — minced oath, "I'll be buggered". ((Partridge HS.))

Grecian bends — properly Grecian bend: (("the body bent forward in walking: a Society vogue of ca 1872–80. The term long outlasted the craze" – Partridge.)) (("An affectation in walking, with the body stooped slightly forward, assumed by English ladies in 1875. The silliness spread to America and other countries which affect passing oddities of fashion" - Brewer 1898.))

brown titus — a misrendering of "bronchitis".

font wants filling — is in need of replenishing with holy water.

Methody — a Methodist. ((Slanguage.)) ((dialect and semi-literate colloquial – Partridge.)) (("You've been getting yourself preached at by them ranting Methody folks on the green" – Messenger of the Sacred Heart of Jesus, 1880.))

cheeses — minced oath, "Jesus!"

pucker — excellent. ((Anglo-Indian colloquial Ex Hindu pakka, "substantial" – Partridge HS.)) This is a British Army usage: in Ireland the usage would be rare.

Brougham

brougham — a one-horse closed carriage. ((OED.)) It's hard to see why a bishop in particular would have a brougham. ((Wikipedia.))